The demands for large-signal handling capability in radiotelephones and in particular cellular phone circuits such as low-noise amplifiers and mixers are increasing, while the supply voltages on which they are required to operate are decreasing. For example, a few years ago battery voltages of 4.8 volts were common, whereas today cellular phone circuits may be required to operate from a 2.7 volt supply.
The lower supply voltage can make it difficult to design large-signal handling circuits around standard integrated circuit mixer configurations, such as Gilbert cells, which usually require a number of active devices to be stacked between the supply rails in order to be current efficient. These active devices may include, for example, the transistors of an input amplifier by means of which unbalanced or single-ended radio frequency received signals are amplified and phase-split to provide the balanced or differential current signals required to drive the transistors of a mixer cell.